Robot and substrate shape abnormality examination method

ABSTRACT

A robot that transfers a substrate includes an arm, a hand, a substrate detector, and a substrate shape abnormality examiner. The hand is installed to the arm and holds and transfers the substrate. The substrate detector detects absence or presence of the substrate in a non-contact manner. The substrate shape abnormality examiner examines the substrate for a shape abnormality based on a height detected by the substrate detector at which the substrate is located when it is not held by the hand.

TECHNICAL FIELD

The present disclosure chiefly relates to a robot that transfers substrates, such as semiconductor wafers and printed circuit boards. More particularly, the present disclosure relates to a configuration for detecting an abnormality in shape of a substrate to be transferred before holding it.

BACKGROUND ART

Conventionally, there has been a known robot for transferring a substrate that takes out a substrate from a substrate storage apparatus, a substrate processing apparatus, or the like, and transfers it. PTL 1 discloses a wafer transfer apparatus, which is a robot of this type.

The wafer transfer apparatus of PTL 1 includes an orientation detector that detects an orientation of a hand, and an actuator. In this wafer transfer apparatus, the orientation of the hand is adjusted by controlling a degree of expansion and contraction of the actuator based on information of the orientation of the hand detected by the orientation detector.

PRIOR-ART DOCUMENTS Patent Documents

-   PTL 1: Japanese Patent Application Publication No. 2004-128021

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

In recent years, due to reasons, such as thinner wafers, a warpage of a substrate, a type of a shape abnormality, has become more likely to occur. However, in PTL 1, the orientation detector only detects an orientation of the hand and cannot detect a warpage of a substrate before it is held by the hand. If the substrate is warped, the substrate may be damaged during the process of being held by the robot.

The present disclosure is made in view of the situation described above, and its purpose is to accurately determine whether a shape abnormality of a substrate to be transferred has occurred before a robot takes out the substrate and holds it.

Means for Solving the Problems

The problem to be solved by the present disclosure is as described above. The means to solve this problem and the effects thereof will be described below.

A first aspect of the present disclosure provides a robot with a configuration described below. That is, a robot that transfers a substrate includes an arm, a hand, a substrate detector, and a substrate shape abnormality examiner. The hand is installed to the arm and holds and transfers the substrate. The substrate detector detects absence or presence of the substrate in a non-contact manner. The substrate shape abnormality examiner examines the substrate for a shape abnormality based on a height detected by the substrate detector at which the substrate is located when it is not held by the hand.

A second aspect of the present disclosure provides a substrate shape abnormality examination method as follows. That is, in this substrate shape abnormality examination method, a robot that transfers the substrate examines the substrate for a shape abnormality. The robot includes an arm, a hand, and a substrate detector. The hand is installed to the arm and holds and transfers the substrate. The substrate detector detects absence or presence of the substrate in a non-contact manner. The substrate is examined for a shape abnormality based on a height detected by the substrate detector at which the substrate is located when it is not held by the hand.

In these manner, an examination of the substrate for a shape abnormality can be made before it is took out from a substrate storage apparatus or the like. Therefore, when the hand moves, unintended contact between the hand and the substrate that occurs due to an abnormality of the substrate in its shape can be avoided. As a result, the substrate can be prevented from, for example, being damaged.

Effects of the Invention

According to the present disclosure, whether a shape abnormality of the substrate to be transferred has occurred can be accurately determined before the robot takes out the substrate and holds it.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing an overall configuration of a robot according to one embodiment of the present disclosure.

FIG. 2 is a perspective view showing an example of a tilter.

FIG. 3 is a cross-sectional view showing an example of a tilter.

FIG. 4 is a drawing illustrating a robot examining an orientation of a substrate.

FIG. 5 is an enlarged drawing illustrating a robot hand moving up and down with respect to a substrate.

FIG. 6 is an illustrative drawing showing changes in a detected thickness due to a warpage of a substrate.

FIG. 7 a drawing conceptually illustrating an orientation of a detection axis of a mapping sensor being changed in order to determine whether a substrate is warped or not.

FIG. 8 is a plan view illustrating an examination of a substrate for a warpage in a variation.

EMBODIMENT FOR CARRYING OUT THE INVENTION

The disclosed embodiments will be described below with reference to the drawings. FIG. 1 is a perspective view showing an overall configuration of a robot 100 according to one embodiment of the present disclosure.

The robot 100 shown in FIG. 1 is installed, for example, in a plant for the manufacture of a substrate W, such as a semiconductor wafer or a printed circuit board, or in a warehouse for storing the substrate W. The robot 100 is used to transfer the substrate W between a substrate processing apparatus and a substrate storage apparatus 7 which is described below. Note, however, that the robot 100 may also be used, for example, to transfer the substrate W between multiple substrate processing apparatuses that process the substrate W. The substrate W may be any of the following: a raw material for a substrate, a semi-finished product in process, or a finished product. The substrate W is disc-shaped in the present embodiment, but is not limited to this.

The robot 100 chiefly includes a base 1, a robot arm (an arm) 2, a robot hand (a hand) 3, and a robot controller (a substrate shape abnormality examiner) 9.

The base 1 is fixed to a floor of a factory or the like. Note, however, that the base 1 may also be fixed, for example, to a casing of a substrate processing facility equipped with the aforementioned substrate processing apparatus, without limitation. The base 1 may also be fixed to a moving cart, which is not shown in the drawings, that travels between the substrate processing apparatus (or facility) and the substrate storage apparatus 7.

As shown in FIG. 1 , the robot arm 2 is installed to the base 1 with a lifting shaft 11 that can move in the vertical direction installed between them. The robot arm 2 can rotate with respect to the lifting shaft 11.

The robot arm 2 includes a horizontal articulated robot arm. The robot arm 2 includes a first arm 21 and a second arm 22.

The first arm 21 is comprised of an elongated member extending in a horizontal direction. One end of the first arm 21 in the lengthwise direction is installed to the upper end of the lifting shaft 11. The first arm 21 is rotatably supported to rotate around the (vertical) axis of the lifting shaft 11. The second arm 22 is installed to the other end of the first arm 21 in the lengthwise direction.

The second arm 22 is comprised of an elongated member extending in a horizontal direction. One end of the second arm 22 in the lengthwise direction is installed to the distal end of the first arm 21. The second arm 22 is rotatably supported to rotate about an (vertical) axis parallel to the lifting shaft 11. The robot hand 3 is installed to the other end of the second arm 22 in the lengthwise direction.

Each of the lifting shaft 11, the first arm 21 and the second arm 22 is driven by a suitable actuator, not shown in the drawings. These actuators may be, for example, electric motors.

Arm joints are located between the lifting shaft 11 and the first arm 21, between the first arm 21 and the second arm 22, and between the second arm 22 and the robot hand 3. An encoder, not shown in the drawings, is installed at each arm joint and detects rotational position of each of the first arm 21, the second arm 22 and the robot hand 3. Also, at an appropriate location on the robot 100, an encoder that detects changes in the position of the first arm 21 in the height direction (i.e., an amount of lift of the lifting shaft 11) is installed.

Based on positional information of the first arm 21, the second arm 22, or the robot arm 3 including information about their rotational position or vertical position detected by the corresponding encoder, the robot controller 9 controls the operation of the electronic motors that each drive one of the lifting shaft 11, the first arm 21, the second arm 22, and the robot hand 3. In the following description, the term “positional information” detected by the encoders shall mean a combination of positional information detected by each encoder that represents the pose of the robot 100.

The robot hand 3 includes a wrist 31 and a hand body 32, as shown in FIG. 1 .

The wrist 31 is attached to the distal end of the second arm 22 with a tilter 4 installed between them. The wrist 31 is rotatably supported to rotate about an (vertical) axis parallel to the lifting shaft 11. Note, however, that the axis of rotation of the wrist 31 can be tilted with respect to a line parallel to the lifting shaft 11 by using the tilter 4. The configuration of the tilter 4 is described in detail below. The wrist 31 is rotationally driven by a suitable actuator that is not shown in the drawings. This actuator may be, for example, an electric motor. The hand body 32 is connected to the wrist 31. The wrist 31 and the hand body 32 may be provided as one integrally formed member.

The hand body 32 is a member that acts in order to hold the substrate W. The hand body 32 includes a plate-like member formed in a Y-shape (or a U-shape). One end portion of the hand body 32 which is not connected to the wrist 31 (in other words, the distal portion) is split in two. In the following description, each of the bifurcated portions may be referred to as a first finger 32 a and a second finger 32 b.

The first finger 32 a and the second finger 32 b are formed to be symmetrical with each other. As shown in FIG. 4 and FIG. 5 , a suitable distance is formed between the tips of the first finger 32 a and the second finger 32 b. This allows the edge of the substrate W to be positioned between the tips of the first finger 32 a and the second finger 32 b without the robot hand 3 coming into contact with the substrate W.

More than one guide member 33 for holding the substrate W is installed both on the distal portion and on the proximal portion of the hand body 32 of the present embodiment. The guide members 33 are comprised of, for example, rubber. The guide members 33 are installed to project upward from the hand body 32, which is a plate-like member. For example, as shown in FIG. 1 , one guide member 33 is installed on each of the first finger 32 a and the second finger 32 b, and two guide members 33 are installed on the proximal end portion of the hand body 32.

As shown in FIG. 1 , the guide members 33 contact portions of the bottom surface of the substrate W close to its rim and they hold the substrate W placed on the robot hand 3. By contacting the rim of the substrate W from the outside of the substrate W in the radial direction, the guide members 33 regulate the substrate W placed on the robot hand 3 so that it does not slide in the horizontal direction.

The configuration of the robot hand 3 to hold the substrate W is not limited to the configuration described above. The robot hand 3 may hold the substrate W by, for example, a structure that suctions the top surface or the bottom surface of the substrate W with negative pressure. For example, the robot hand 3 may be equipped with a known Bernoulli chuck to hold the substrate W in a non-contact manner.

The tilter 4 is installed to the distal portion of the second arm 22 (to the end portion opposite to the other end portion connected to the first arm 21).

The tilter 4 includes a bottom plate 41 and the top plate 42 as shown in FIG. 2 . The bottom plate 41 is fixed to the top surface of the second arm 22. The top plate 42 rotatably supports the wrist 31 of the robot hand 3. A height adjuster 5 is located between the bottom plate 41 and the top plate 42. The tilter 4 adjusts the angle and direction of a tilt of the top plate 42 with respect to the bottom plate 41 by using this height adjuster 5.

The height adjuster 5 includes, for example, three supports 51, 52, 53 arranged at different positions between the bottom plate 41 and the top plate 42 as shown in FIG. 2 . In FIG. 3 , the supports 51, 52, and 53 are drawn as they are positioned in a straight line for convenience of explanation, but in actuality, as shown in FIG. 2 , they are arranged to form a triangle in a plan view.

Each of the supports 51 and 52 includes an externally threaded member 56, an internally threaded member 57, and a spherical bearing 58. The threaded shafts of the externally threaded members 56 are rotatably supported by the bottom plate 41 with their axes pointing in a vertical direction. Actuators (for example, electric motors), that are not shown in the drawings, can separately rotate each of these threaded shafts arranged in the two supports, 51 and 52. Each of the internally threaded members 57 is coupled with the threaded shaft of the corresponding externally threaded member 56. When the threaded shaft is rotated, the corresponding internally threaded member 57 moves in a vertical direction. This movement allows the height at which the supports 51 and 52 support the top plate 42 to be changed. The spherical bearings 58 are located between the internally threaded members 57 and the top plate 42.

A spherical bearing 58 is arranged at the support 53. The support 53 does not have such function to change the height of support by using threads.

With the electric motors driven, the supports 51 and 52 independently change the height of the top plate 42 with respect to the bottom plate 41. In this manner, the angle and the direction of the tilt of the top plate 42 with respect to the bottom plate 41 are changed. As a result, the orientation (the angle and direction of the tilt) of the robot hand 3 with respect to the second arm 22 is adjusted. Note that, the configuration of the height adjuster 5 (and thus the tilter 4) is not limited to this configuration described above.

As shown in FIG. 1 , a mapping sensor (a substrate detector) 6 is arranged at the distal portion of the hand body 32. The mapping sensor 6 allows a check of the presence or absence of the substrate W (that is, mapping) to be done in a non-contact manner. In the present embodiment, the mapping sensor 6 is comprised of, for example, a through-beam sensor including a light emitter 61 and a light receiver 62. Without limitation, the mapping sensor 6 may also be comprised of, for example, a reflective sensor.

As shown in FIG. 1 and in FIG. 4 , the light emitter 61 is installed on the distal portion of the first finger 32 a. The light receiver 62 is installed on the distal portion of the second finger 32 b. The light emitter 61 emits a detection light toward the light receiver 62. The detection light may be, for example, but not limited to, infrared light.

The light receiver 62 is connected to the robot controller 9 wirelessly or by wire. The light receiver 62 outputs an electrical signal to the robot controller 9 indicating whether or not the detection light is received. When there is no object (for example, the substrate W) between the light emitter 61 and the light receiver 62, the detection light emitted from the light emitter 61 reaches the light receiver 62 and the light receiver 62 outputs an electrical signal indicating that the light is received. When there is an object between the light emitter 61 and the light receiver 62, the detection light emitted from the light emitter 61 is blocked by the substrate W, and the light receiver 62 outputs an electrical signal indicating that the light is not received.

When a plurality of spaces for placing the substrate W are arranged at suitable intervals in the vertical direction in the substrate storage apparatus 7, the robot controller 9 moves the robot hand 3 in the vertical direction across these spaces for placing, keeping the distal end of the robot hand 3 close to these spaces (mapping operation). At this time, the robot hand 3 is placed at such a position in a plan view that, when the substrate W is placed in the said space, the robot hand 3 is out of contact with the substrate W and the mapping sensor 6 can detect the substrate W. Based on the time-series data output from the mapping sensor 6 while the robot hand 3 is moved in the vertical direction, the presence or absence of the substrate W at each space for placing can be determined.

However, it is not limited to the above configuration. For example, when the robot hand 3 is moved in the vertical direction, the presence or absence of the substrate W may be determined corresponding to the positional information detected by the encoders, based on the output form the mapping sensor 6 corresponding to each position of the robot hand 3. In this case, the information about the presence or absence of the substrate W obtained from the output of the mapping sensor 6 and the positional information detected by the encoders are associated with each other.

As long as the light receiver 62 can detect the light emitted from the light emitter 61, the light emitter 61 and the light receiver 62 may be located any places of the robot hand 3. For example, the light emitter 61 may be built into the first finger 32 a and the light receiver 62 may be built into the second finger 32 b.

As shown in FIG. 1 , the robot controller 9 is arranged separately from the base 1. Note, however, that the robot controller 9 may be arranged inside the base 1. The robot controller 9 is configured as a known computer and includes a processing unit, such as a microcontroller, a CPU, a MPU, a PLC, a DSP, an ASIC or a FPGA, a memory unit, such as a ROM, a RAM or a HDD, and a communication unit that can communicate with an external apparatus. The memory unit stores a program to be executed by the processing unit, various thresholds, data on the shape of the substrate W to be transferred, such as thickness and size, or the like. The communication unit is configured to transmit results of the detection made by various sensors (for example, the mapping sensor 6 and the encoders) to the external apparatus and to receive the information about the substrate W or the like from the external apparatus.

The examination of the substrate W for a shape abnormality by the robot 100 of the present embodiment will be described in detail below with reference to the drawings from FIG. 4 to FIG. 6 . In the following description, some configurations may be omitted in the drawings in order to illustrate each configuration of portions in a comprehensible way. The following description will be with reference to an example wherein a warpage, an example of a shape abnormality, of the substrate W stored in the substrate storage apparatus 7 is detected. There are various possible shape abnormalities of the substrate W other than a warpage of the substrate W. For example, a change in shape of the substrate W due to a foreign substance that adheres to the substrate W is a type of a shape abnormality. An increase in thickness of the substrate W due to an unintended formation of a film on the surface of the substrate W is also a type of a shape abnormality.

The substrate storage apparatus 7 shown in FIG. 4 is used to store the substrates W. In the substrate storage apparatus 7, a plurality of substrates (for example, 100 or more substrates) are placed at regular intervals in the vertical direction (i.e., the heightwise direction of the substrate storage apparatus 7) and stored.

In the substrate storage apparatus 7, the substrates W are usually stored in horizontal poses. However, for some reason, such as deformation of a shelf or presence of a foreign substance, sometimes the substrate W is stored in the substrate storage apparatus 7, having a non-horizontal orientation. Furthermore, there may be cases where a shape abnormality of the substrate W has occurred. The robot 100 of the present embodiment can examine the substrate W for a warpage, an example of a shape abnormality, before taking the substrate W out from the substrate storage apparatus 7.

Although a warpage (curvature) of the substrate W can occur three-dimensionally, in the present embodiment, a warpage of the substrate W with respect to a horizontal plane observed with a line of sight along the direction in which the robot hand 3 is inserted into the substrate storage apparatus 7 (hereinafter, this direction is referred to as “the hand insertion direction”) is examined.

Specifically, as shown in FIG. 4 , the robot controller 9 moves the robot hand 3 so that a portion of the substrate W to be examined is positioned between the first finger 32 a and the second finger 32 b, keeping the hand body 32 horizontal. At this time, the detection light emitted from the mapping sensor 6 is directed so as to be parallel to the suitable orientation of the substrate W.

Then, the robot controller 9 drives the lifting shaft 11 to move in the vertical direction in order to move the robot hand 3 vertically keeping it horizontal. As a result, a vertical scan is accomplished by the mapping sensor 6. For example, as shown in FIG. 5 , the robot hand 3 moves from below to above or from above to below the substrate W. It is preferable to keep a speed of the movement of the robot hand 3 constant at this time in terms of ease of calculation of a detected thickness TH1 which is described below.

When a portion of the substrate W passes between the first finger 32 a and the second finger 32 b of the robot hand 3, the light emitted from the light emitter 61 is blocked by the substrate W. As a result, the output signal of the light receiver 62 changes, for example, as shown in the graphs in FIG. 5 .

The robot controller 9 calculates an interrupted time t0 during which the light emitted from the light emitter 61 is interrupted by the substrate W while the robot hand 3 is moved in the vertical direction by analyzing time-series data which is based on the output of the light receiver 62. The interrupted time to can be referred to as a time of detection for which the mapping sensor 6 detects the presence of the substrate W. The robot controller 9 calculates a distance in which the robot hand 3 moves in the vertical direction during the calculated interrupted time to and determine it as a detected thickness TH1 of the substrate W to be examined. The detected thickness TH1 corresponds to the difference between the maximum value and the minimum value of the heights at which the presence of the substrate W is detected. Note that, as the robot hand 3 is vertically moved, the detected thickness TH1 of the substrate W to be examined may also be calculated based on the output from the mapping sensor 6 corresponding to each portion of the robot hand 3 and the positional information detected by the encoders.

As shown in FIG. 6 , when the substrate W is placed horizontally with respect to the robot hand 3 and the substrate W is not warped, a distance in which the robot hand 3 moves during the light emitted from the light emitter 61 is interrupted equals an actual thickness TH of the substrate W. On the other hand, when the substrate W is tilted with respect to the robot hand 3 or a warpage of the substrate W has occurred, a distance in which the robot hand 3 moves during the light emitted from the light emitter 61 is interrupted exceeds the actual thickness TH of the substrate W.

The robot controller 9 compares the detected thickness TH1 of the substrate W calculated as described above with the actual thickness TH of the substrate W memorized by the memory unit and determines whether the substrate W to be examined is warped or not using the above-described theory.

There are various method for the determination. For example, the determination may be made by comparing the difference between the detected thickness TH1 and the actual thickness TH of the substrate W to be examined with the predetermined threshold. In this case, the robot controller 9 determines that the substrate W to be examined is tilted or warped when the difference between them exceeds the threshold.

The actual thickness TH of the substrate W may be calculated in advance based on data, such as a design data and a manufacturing data of the substrate W. Also, an average of thicknesses obtained by measuring more than one substrate W may be used as the actual thickness TH. Also, the actual thickness TH of the substrate W may be received by the robot controller 9 from an external apparatus via the communication unit in advance and stored in the memory unit.

When the substrate W to be examined is tilted or warped, the robot controller 9 tilts the orientation of the detection light of the mapping sensor 6 in the roll direction with respect to the hand insertion direction by suitably tilting the robot hand 3 with respect to a horizontal plane. Then the robot controller 9 moves the robot hand 3 up and down again to obtain the renewed detected thickness TH1. The detected thickness TH1 is acquired multiple times with the direction and magnitude of the tilt of the detection light in the roll direction suitably varied at each time. FIG. 7 conceptually shows how the detected thickness TH1 is acquired with the orientation of the detection light of the mapping sensor 6 varied.

As shown in FIG. 7 , if the substrate W is tilted but not warped, the detected thickness TH1 becomes almost equal to the actual thickness TH when the detection light of the mapping sensor 6 is parallel to the substrate W with respect to its tilt angle θ. On the other hand, if the substrate W is warped, the detected thickness TH1 becomes larger as the substrate W is warped than the actual thickness TH even when the detection light of the mapping sensor 6 is substantially aligned with the substrate W.

In the present embodiment, the direction in which the mapping sensor 6 scans the substrate W is constant, that is, the vertical direction, regardless of the orientation of the detection light of the mapping sensor 6. The cross-section of the substrate W in a normal shape cut by a vertical plane parallel to the hand insertion direction is larger when the substrate W is tilted than when it is horizontal. Similarly, the detected thickness TH1 will be slightly larger than the actual thickness TH even when the substrate W is only tilted and not warped. In this case, the detected thickness TH1 can be corrected based on the tilt angle θ or the like.

When more than one detected thickness TH1 are obtained, the robot controller 9 finds a minimum value of the difference between the detected thickness TH1 and the actual thickness TH. If this minimum value is less than or equal to the predetermined warpage threshold, the robot controller 9 determines that the substrate W is only tilted in the roll direction and is not warped. If the minimum value is larger than the warpage threshold, the robot controller 9 determines that the substrate W is warped.

When it is determined that the substrate W is warped, the robot controller 9 performs appropriate control. Examples of the control may include excluding the substrate W concerned from targets to be transferred or stopping its operation. In this manner, the robot hand 3 does not insert itself into a space below the warped substrate W in the substrate storage apparatus 7 so that the substrate W and the robot hand 3 do not come into contact with each other and the substrate W is prevented from, for example, being damaged.

As described above, the robot 100 of the present embodiment is used to transfer the substrate W. The robot 100 includes the robot arm 2, the robot hand 3, the mapping sensor 6, and the robot controller 9. The robot hand 3 is installed to the robot arm 2 and holds and transfers the substrate W. The mapping sensor 6 detects the presence or absence of the substrate W in a non-contact manner. The robot controller 9 examines the substrate W for a warpage based on a height detected by the mapping sensor 6 at which the substrate W is located when it is not held by the robot hand 3.

This allows an examination of the substrate W for a warpage to be made before the substrate W is taken out from an apparatus, such as the substrate storage apparatus 7. Therefore, unintended contact between the robot hand 3 and the substrate W due to a warpage of the substrate W is prevented from occurring while the robot hand 3 is moving. As a result, the substrate W is prevented from, for example, being damaged.

In the robot 100 of the present embodiment, the mapping sensor 6 is installed to the robot hand 3 in order to detect the presence of the substrate W by using the detection light. Based on the output from the mapping sensor 6 with the robot hand 3 moved vertically, the robot controller 9 obtains the detected thickness TH1 which is a difference between the maximum value and the minimum value of heights at which the presence of the substrate W is detected. The robot controller 9 performs this process multiple times varying the orientation of the detection light of the mapping sensor 6 at each time. The robot controller 9 examines the substrate W for a warpage based on the minimum value of the difference between the detected thickness TH1 and the actual thickness TH of the substrate W.

This allows an easy and accurate examination of an orientation of the substrate W with a simple configuration.

The robot 100 of the present embodiment also includes the tilter 4 that tilts an orientation of the robot hand 3 in a desired direction.

This allows an orientation of the mapping sensor 6 to be adjusted with a great flexibility.

Next, a variation of the embodiment described above will be explained below. FIG. 8 is a plan view illustrating an examination of the substrate W for a warpage in the present variation. In the description of the present variation, the same or similar components as that of the above-described embodiment may be marked with the same references in the drawings and the description thereof may be omitted.

The robot 100 of the present variation includes a rangefinder 6 x in addition to the mapping sensor 6. The rangefinder 6 x and the mapping sensor 6 are comprised in the substrate detector. The rangefinder 6 x is used for detection of a warpage of the substrate W with respect to a horizontal plane observed with a line of sight along a direction perpendicular to the said hand insertion direction.

The rangefinder 6 x includes, for example, a laser displacement meter or an ultrasonic distance sensor. The rangefinder 6 x is, as shown in FIG. 8 , for example, installed on the top surface of the second finger 32 b of the hand body 32. The rangefinder 6 x detects a vertical distance between the rangefinder 6 x itself and the bottom surface of the substrate W in a non-contact manner. The rangefinder 6 x is connected to the robot controller 9 wirelessly or by wire, and transmits data of the distance to the substrate W measured at the measurement position to the robot controller 9.

The robot controller 9 inserts the robot hand 3 below the substrate W supported in the substrate storage apparatus 7. In this manner, the rangefinder 6 x faces the substrate W vertically. Note that the guide member 33 does not hold the substrate W at this time. By moving the robot hand 3 horizontally along the hand insertion direction, the robot controller 9 measures distances between the rangefinder 6 x and the substrate W to be examined at least three points.

Based on differences of the heights of the substrate W measured by the rangefinder 6 x at three points at least, the robot controller 9 determines whether the substrate W is warped. This determination may be made, for example, by a geometric calculation that finds out whether the three points are in the same straight line or not.

When the substrate W is absent, the rangefinder 6 x measures an abnormal value. Therefore, the rangefinder 6 x can be considered as a sensor that can substantially detect the presence or absence of the substrate W.

In the above-described embodiment, the mapping sensor 6 examines for a warpage of the substrate W as observed with a line of sight along the hand insertion direction. In addition, in the present variation, the rangefinder 6 x examines for a warpage of the substrate W with respect to a horizontal plane as observed with a line of sight along a direction perpendicular to the hand insertion direction. Thus, in the present variation, the presence or absence of a warpage of the substrate W can be examined three-dimensionally.

As described above, in the robot 100 of the present variation, the rangefinder 6 x is installed to the hand body 32 in order to measure a vertical distance to the substrate W. The robot controller 9 examines the presence or absence of a warpage of the substrate W based on each of the distances measured by the rangefinder 6 x at multiple points of the substrate W.

This allows an easy and accurate examination of the presence or absence of a warpage of the substrate W with a simple configuration.

While the preferred embodiment and the variations of the present disclosure have been described above, the configurations described above may be modified as follows, for example.

The robot 100 may hold an object, such as a tray carrying the substrate W, instead of directly holding the substrate W to transfer.

The hand body 32 of the robot hand 3 may be integrally formed with the top plate 42 of the tilter 4.

The tilter 4 may be arranged between the base 1 and the lifting shaft 11, or between the lifting shaft 11 and the first arm 21, or between the first arm 21 and the second arm 22.

Regardless of whether the substrate W is warped or not, the robot controller 9 may calculate a tilt angle of the substrate W based on the output of the mapping sensor 6 and the rangefinder 6 x.

In the first variation shown in FIG. 8 , the mapping sensor 6 may be omitted. In this case, the presence or absence of a warpage of the substrate W with respect to a horizontal plane as observed with a line of sight along a direction perpendicular to the hand insertion direction can still be examined with the rangefinder 6 x horizontally scanning the substrate W along the hand insertion direction. Also, to examine for a warpage of the substrate W, the rangefinder 6 x may measure heights of, for example, nice points on the substrate W that is in a matrix in a plan view, with the robot hand 3 horizontally moved. In this case, the presence or absence of a warpage of the substrate W can be three-dimensionally examined by using only the rangefinder 6 x.

The presence or absence of a warpage of the substrate W may be examined by an apparatus other than the robot controller 9.

The functionality of the elements disclosed herein may be implemented using circuitry or processing circuitry which includes general purpose processors, special purpose processors, integrated circuits. ASICs (“Application Specific Integrated Circuits”), conventional circuitry and/or combinations thereof which are configured or programmed to perform the disclosed functionality. Processors are considered processing circuitry or circuitry as they include transistors and other circuitry therein. The processor may be a programmed processor which executes a program stored in a memory. In the disclosure, the circuitry, units, or means are hardware that carry out or are programmed to perform the recited functionality. The hardware may be any hardware disclosed herein or otherwise known which is programmed or configured to carry out the recited functionality. When the hardware is a processor which may be considered a type of circuitry, the circuitry, means, or units are a combination of hardware and software, the software being used to configure the hardware and/or processor.

In view of the foregoing teachings, it is clear that the present disclosure may take many modified and variant forms. Therefore, it is to be understood that the present disclosure may be practiced in a manner other than that described herein, within the scope of the appended claims. 

1. A robot that transfers a substrate, comprising: an arm; a hand that is installed to the arm and holds and transfers the substrate; a substrate detector that detects absence or presence of the substrate in a non-contact manner; and a substrate shape abnormality examiner that examines the substrate for a shape abnormality based on a height detected by the substrate detector at which the substrate is located when it is not held by the hand.
 2. The robot according to claim 1, wherein the substrate detector includes a mapping sensor installed to the hand in order to detect the absence or presence of the substrate by using a detection light, and wherein the substrate shape abnormality examiner performs a process of calculating a maximum value and a minimum value of heights at which the presence of the substrate is detected based on output from the mapping sensor with the hand moved vertically, and obtaining a detected thickness which is a difference between the maximum value and the minimum value and the process is performed multiple times with an orientation of the detection light varied, and wherein absence or presence of the shape abnormality of the substrate is examined based on a minimum value of a difference between a detected thickness and an actual thickness of the substrate.
 3. The robot according to claim 1, comprising a tilter that tilts an orientation of the hand in a desired direction.
 4. The robot according to claim 1, wherein the substrate detector includes a rangefinder that is installed to the hand in order to measure a vertical distance to the substrate, and wherein the substrate shape abnormality examiner examines the absence or presence of the shape abnormality of the substrate based on each of distances measured by the rangefinder at multiple points of the substrate.
 5. A substrate shape abnormality examination method applied to a robot that transfers a substrate and includes: an arm; a hand that is installed to the arm and holds and transfers the substrate; and a substrate detector that detects absence or presence of the substrate in a non-contact manner, wherein the substrate is examined for a shape abnormality based on a height detected by the substrate detector at which the substrate is located when it is not held by the hand. 